422 FLIGHT International, 28 September (972
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V for two
By ANDREW HOFTON
WITHIN HOURS of an armed confrontation in Europe, Nato airfields could be destroyed by pre-targeted strikes by hostile aircraft. In this situation the
RAF's Harriers operating from dispersed sites could be
the only fixed-wing tactical aircraft, flying from forward
bases, available to Allied commanders to arrest the pro
gress of enemy armour. Against this sobering background,
and constrained by limited defence budgets, the Ministry
of Defence demanded, and Hawker Siddeley supplied, the
most cost-effective solution to the requirement for a two-
seat Harrier. The fully operational T.2, with identical
weapon-carrying capacity and very similar performance to
the GR:1, would fight alongside the single-seat aircraft of
Nos 1, 3, 4 and 20 Squadrons in a "for real" war situation.
Surprisingly, it was not the demands of vertical take-off
and landing which suggested the need for a two-seat
trainer. A large number of pilots had flown the P.1127,
Kestrel and GR.l without this aid, and Hawker Siddeley
is certain that the GR.l is sufficiently simple to be flown
by first-tour and militia pilots. The need to teach aircrew
to make full use of the Harrier weapon system's unique
capabilities, such as operation from sites close to the for
ward battle area, and to use thrust vectoring during com
bat manoeuvres suggested the two-seat requirement. The
T.2 not only improves the proficiency of front-line
squadrons but also allows designers, policy makers and
potential customers to sample the realities of Vtol.
A comparison of the GR.l cutaway published in Flight
for November 2, 1967, and the structure of the T.2, which
has the optional bolt-on ferry tips and in-flight refuelling
probe, shows wing, tailplane, centre fuselage (between
frames 8 and 43), items of equipment and structural
philosophy remaining substantially unchanged. An article
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Duncan Simpson brings the T.2 in close to show off details of the canopy
and forward fuselage. The front and rear unstretched acrylic canopies
are operated manually and open sideways. XWI75 proudly displays the
HS logo on the nose and has the latest-type RAF roundels on the wings
and intakes. XWI75 was the second pre-production two-seat Harrier
T.2 and has been used for much of the development flying associated
with stability and control. The extended tailcone carries a brakejanti-
spin parachute and is a standard fit for all development flying, but is
not carried by service Harriers. Flaps are down to help keep formation
with Tom Hamill in the RAE's Hastings
on the Rolls-Royce Pegasus, including cutaway drawing,
will follow on October 19. No attempt has therefore been
made to repeat the descriptions given in the previous
features. Major differences are limited to the nose, forward
fuselage, fin and rudder of the T.2. Flown by a single pilot
from the front cockpit with the rear ejection seat removed,
the T.2 weighs approximately 8001b, 363kg more than the
GR.l. In the training configuration with two crew and
ballast in the tail the difference rises to 1,4001b, 625kg.
Ballast, which is carried in the end of the tailcone, is used
to maintain the correct centre-of-gravity/centre-of-thrust
relationship in Vtol to avoid excessive reaction-control
bleed, and to keep the correct aerodynamic-centre/centre-
of-gravity relationship in conventional flight.
Unlike the two-seat Hunter, a tandem arrangement was
chosen for the Harrier T.2, and the front cockpit of the
GR.l, from the sloping bulkhead carrying the Martin-
Baker "zero zero" Type 9A Mkl rocket-assisted ejection
seat, has been moved forward by 47in, 120cm. The rear
seat has been located 7in, 18cm aft of the GR.l seat frame
and moved upwards 18in, 46cm relative to the front pilot's
eye datum. While front-seat forward vision remains un
affected, the rear pilot has a good forward and downward
view off the aircraft centre line to each side. The front-
cockpit quarter lights and windscreen forward of the
forged windscreen frame are unchanged but the rfein, 8mm
unstretched acrylic canopy is hinged to open sideways in
two pieces.
The layouts of the front and rear cockpits of the T.2 are
similar to that of the GR.l to assist pilot familiarisation.
When the aircraft is flown two-up the rear pilot will
usually be in command, and some rear-cockpit controls
have over-riding authority. When it is flown solo from the
front, however, most of the rear over-ride controls do
not require pre-setting, while those that do are entered on
a check list displayed in the rear cockpit for ground crew
use in turn-round servicing and role changes.
In order to allow movement of the rear ejection seat
aft of the GR.l seat frame, the cabin environmental equip
ment system has been repackaged in a fairing behind the
new canopy. The new system, which is easily removed for
servicing, has a capacity of 351b/min, 15-9kg/min at sea-
level high-speed cruise (the design condition), to meet the
demands of the new cabin which has a pressurised volume
of 85 cu ft, 2 • 4m3 compared with the 41 cu ft, 1 • lm3 of
the GR.l. Apart from larger pipe diameters to meet the
new flow requirements, the T.2 system has a redesigned
water separator, primary and secondary heat exchanger
and cold-air unit.
The positions of the Ferranti inertial platform, F.95
camera, the q-feel unit and windscreen-washing-fluid tank
continued on page 422a